With the development of science and technology, the projector has an increasingly wider range of applications and it is no longer limited to be installed on the table top or by ceiling mount manner. When a picture is needed to be projected onto a ceiling or floor, the projector must be installed in a manner enabling an upward projection or downward projection. When a picture is needed to be displayed in portrait direction, the projector is required to be installed in a portrait-mode or beam-up/beam-down manner. For a projector employing a high pressure mercury lamp as a light source, there are different cooling ways for the lamp depending on the different manners in which the projector is installed (for example, on a table top, by the ceiling mount manner, upward/downward projection, portrait mode or beam-up/beam-down manner, etc.), so as to achieve a certain lifetime of the lamp. When installed in different manners (such as those manners described above), a projector requires different cooling conditions for its lamp. Therefore, changing the installation manner of a projector whenever the projection angle is required to be switched may result poor cooling and may further compromise the lifetime of the lamp significantly. For the occasion where the projection angle needs to be frequently switched, how to resolve the above-mentioned problems remains a focus of interest for those ordinarily skilled in the art.
The information disclosed in this “BACKGROUND OF THE INVENTION” section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in this “BACKGROUND OF THE INVENTION” section does not mean that one or more problems to be solved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art.